diff --git a/lib/ostruct.rb b/lib/ostruct.rb
index a8763da..e8ab721 100644
--- a/lib/ostruct.rb
+++ b/lib/ostruct.rb
@@ -383,6 +383,32 @@ def delete_field(name, &block)
     end
   end
 
+
+  # Returns +true+ if the given name is a member of this OpenStruct object, +false+ otherwise.
+  # The given +name+ is converted to a symbol before checking.
+  #
+  #   require "ostruct"
+  #   person = OpenStruct.new("name" => "John Smith", :age => 70)
+  #   person.include?(:name)   # => true
+  #   person.include?("age")   # => true
+  #   person.include?(:phone)  # => false
+  #
+  # This method can be used to test for the presence of a value without creating
+  # an accessor method if it doesn't exist:
+  #
+  #   person = OpenStruct.new
+  #   person.name = "John"
+  #   person.include?(:name)   # => true
+  #   person.include?(:age)    # => false
+  #   person.age               # => nil (but creates an accessor)
+  #   person.include?(:age)    # => false
+  #
+  def include?(name)
+    @table.has_key?(name.to_sym)
+  end
+  alias_method :has_key?, :include?
+  alias_method :key?, :include?
+
   InspectKey = :__inspect_key__ # :nodoc:
 
   #
diff --git a/test/ostruct/test_ostruct.rb b/test/ostruct/test_ostruct.rb
index 616f84d..a31e7d1 100644
--- a/test/ostruct/test_ostruct.rb
+++ b/test/ostruct/test_ostruct.rb
@@ -439,4 +439,65 @@ def test_performance_warning
       )
     end
   end
+  def setup
+  end
+
+  def test_has_key_alias
+    o = OpenStruct.new(name: "John Smith", age: 70)
+    assert_equal o.include?(:name), o.has_key?(:name)
+    assert_equal o.include?("name"), o.has_key?("name")
+    assert_equal o.include?(:missing), o.has_key?(:missing)
+  end
+
+  def test_include_with_symbol
+    o = OpenStruct.new(name: "John Smith", age: 70, pension: 300)
+    assert_true o.include?(:name)
+    assert_true o.include?(:age)
+    assert_true o.include?(:pension)
+    assert_false o.include?(:address)
+  end
+
+  def test_include_with_string
+    o = OpenStruct.new(name: "John Smith", age: 70, pension: 300)
+    assert_true o.include?("name")
+    assert_true o.include?("age")
+    assert_true o.include?("pension")
+    assert_false o.include?("address")
+  end
+
+  def test_include_after_deletion
+    o = OpenStruct.new(name: "John Smith", age: 70, pension: 300)
+    o.delete_field(:name)
+    assert_false o.include?(:name)
+  end
+
+  def test_include_with_nil_value
+    o = OpenStruct.new(name: "John Smith", age: 70, pension: 300)
+    o.pension = nil
+    assert_true o.include?(:pension)
+  end
+
+  def test_include_with_new_ostruct
+    os = OpenStruct.new
+    assert_false os.include?(:any_key)
+  end
+
+  def test_include_after_setting_value
+    o = OpenStruct.new(name: "John Smith", age: 70, pension: 300)
+    o.phone = "123-456-7890"
+    assert_true o.include?(:phone)
+  end
+
+  def test_include_case_sensitivity
+    o = OpenStruct.new(name: "John Smith", age: 70, pension: 300)
+    assert_true o.include?(:name)
+    assert_false o.include?(:Name)
+  end
+
+  def test_key_alias
+    o = OpenStruct.new(name: "John Smith", age: 70)
+    assert_equal o.include?(:name), o.key?(:name)
+    assert_equal o.include?("name"), o.key?("name")
+    assert_equal o.include?(:missing), o.key?(:missing)
+  end
 end